Ok to the untrained eye these could be seen as the same thing. And many people still see a meltdown the same as a tantrum. But there are some key differences.
A tantrum occurs when there is a direct trigger of not getting there own way. Weather it be a lolly pop at the store or a not being able to stay up for a little longer. They scream let it out and then move on, occasionally they refuse to budge and throw themselves on the ground ect.
A melt down occurs when there is a prolonged trigger or multiple triggers causing an overload to the senses. Some times a meltdown can be held in until the person is in a safe and comfortable environment. There often appears to be no reason why the action is occurring.
A melt down can take place over HOURS not just minuets. They can be from just simple crying and screaming to full scale violence and destructive behaviour. Often after one of this prolonged episodes the person is tired and exhausted and depending on how long it lasted can be this way for a day or two. Because even before the meltdown the sensory stimuli is exhausting enough. So once they have been letting off steam for a couple of hours, they are really truly exhausted.
The reason I write about this is because I have had so many comments from mothers of NT children say to me it is just a tantrum all kids do that. Usually at the time I am stunned and can't get a correct response. Or just over trying to explain the differences.
So next time you see that screaming child in a sensory overwhelming environment such as a brightly lit supermarket. Stop and think is it really happening becuase mum said no you can't have a lolly pop.